This was part of Computational Challenges and Optimization in Kinetic Plasma Physics

Implicit, asymptotic-preserving and energy-conserving time integration for particle-in-cell simulation of plasmas with arbitrary magnetization

Lee Ricketson, Lawrence Livermore National Laboratory

Thursday, February 22, 2024


Magnetic confinement fusion reactors feature numerous disparate time-scales, with the gyrofrequency induced by the strong magnetic field among the fastest.  While gyrokinetic models permit stepping over this scale, there is increasing concern that the gyrokinetic ordering may break down in certain key regions of such reactors.  This generates interest in asymptotic-preserving schemes that can recover the gyrokinetic limit when it is valid while still converging to full-orbit dynamics in the limit of small time-step.  We present such a scheme which, in addition to the desired asymptotic properties, preserves the exact energy and charge conservation enjoyed by implicit particle-in-cell (PIC) methods developed over the last decade.  We discuss the scheme’s theoretical development, an efficient and robust nonlinear solver, and numerical results for both single-particle test cases and self-consistent PIC simulations.   * Prepared by LLNL under Contract DE-AC52-07NA27344.